Several parameters are measured in high-purity, industrial water and wastewater treatment applications which include pH, resistivity/ conductivity, total organic carbon and specific ions. These parameters coupled with other measurements permit site operators to establish the quality of treated water and highlight adjustments which may need to be implemented in treatment protocols to prevent issues from arising. This article provides insights into the vital role played by pH instruments including sensor installation and sensor cleaning and calibration, allowing those less familiar with the water business gain a better understanding of this topic.